Motor starting and safety switch



July 5, 1949. A. R. LUCAS MOTOR STARTING AND SAFETY SWITCH Filed Sept.28, 1946 lllllllllllllllllllllllllllllll 1' INVENTOR.

A/ffea A? Lama BY M M arraE'NEZS Patented July 5, 1949 REISSUED MOTORSTARTING AND SAFETY SWITCH Alfred B. Lucas, Gallon, Ohio ApplicationSeptember 28, 1946, Serial No. 700,074

4 Claims.

The present invention relates to electric switches and more specificallyto switches through which current is supplied to motors first to thestarting windings and then the running windings.

Among the objects of the invention is a switch provided with means fordividing the initial current between the two motor windings andsubsequently breaking the circuit through the starting winding,

Another object is a switch provided with means for breaking the motorcircuit under conditions of overload or excessive heating.

Still another object is a switch which automatically restarts the motorwhen the objectionable condition has been relieved.

ther objects and advantages will readily occur to those skilled in theart upon reference to the following description and the accompany ingdrawings in which Fig. l is a top plan view of the switch elements.

Fig. 2 is a side view thereof and also shows diagrammatically the motorconnections.

Fig. 3 is a view similar to Fig. 2 but shows in addition,diagrammatically, means for controlling the timing of the re-start.

Fig. s is a fragmentary section showing the switch of Fig. 3 in openposition.

As shown in the drawing, the switch consists of a base or housing ill ofinsulating material relatively long and having at one end anchoragemeans i l for a pair of spring arms I 2, one on each side of but not incontact with, an arm I3 of bimetalfwhich extends through and projectsfrom the endwall of the member I, the projecting end serving asconnecting means for a lead wire It,

The free end of arm i3 carries a contact Hill exposed on both upper andlower faces oi the arm, while the arm itself is considerably shorterthan the spring arms I 2. The spring arms 62 are fixed at their freeends to a conducting cross member IZA which carries a contact [23exposed on both upper and lower faces of the member IZA.

Located in the end or" the base ill is a short conductor IS the innerend of which carries a contact I 5A in position to onset with thecontact "B and to the outer end of which is connected a lead wire I ii.

In the bottom of the base i0 is another fixed contact ll mounted on aconductor IIA leading from the base or housing and to which is connecteda lead wire l8. This contact I1 is below and in position to coact withthe contact ISA carried'by the bi-metal arm IS. The housin III 2 alsocarries stop members IDA and IOB opposite respectively the contacts ISAand HE.

Mounted between the free end of arm l3 and; the cross member A, is acurved flat spring member 20, this being reversely curved at its ends toform sockets and being made of light spring material. Also extendingbetween the same parts is a flexible lead wire 2 t.

In the use of the switch described above, the lead wire It is connectedto one end of the rim-= ning winding A of a motor while the other end.winding A. is connected to one end of the starting winding and at theirjunction they are connected to a power supply or return line C. The conductor it is directly connected to or is a part of the other power leadD. The conductor iii leads to the other end, or end opposite the runningwinding, of the starting winding B.

When the power leads C and D are not energized and no current is flowingthrough the switch, the parts are in the position shown in full lines inFig. 2. When the current is turned on, the flow from lead (1 will be tothe bl-metal arm it and from this it will be divided and part will go tocontact ill and part through member 28 and flexible lead 2!! to contactWA, so that from lead D the flow of current will be through both thestarting winding B and running winding A, all of the current traversingthe bl metal arm It.

As a consequence, the arm it will be heated rather quickly and thecontact of i 3A with l i will soon be broken. The time, of course, mayreadily be pro-set by using the proper strip for arm it.

With separation of contacts i321 and H, current flow will continuethrough contacts HE, MA, lead it and windings The heating effeet on armit will be at the same time reduced, so that, under usual runningconditions, the arm It will not move up sufiiciently to break the run--ning circuit.

When, however, an overload occurs, and with it an excessive currentflow, the arm is will move further and. cause the toggle spring 20 tosnap over center and separate contacts E23 and ISA, as indicated in Fig.4, and this condition will continue until arm it cools sufiiciently tomove down and cause the toggle spring 20 to again thrust the lattercontacts together.

While it may not be necessary in most cases to delay the re-start for agreater time than that of the natural cooling of arm l3, this time maybe prolounged by such means as is shown in Fig. 3. In this figure, thestops IDA and IOB are shown as contacts NBA and HUB connectedrespectively to leads HI and 2, the former leading to a variableresistance device HA and the latter to any suitable device DD forutilizin the current. This arrangement provides for continuing thecurrent flow through arm l3 when the parts are in the position of Fig. 4and so continues the heating of the arm. It is of course to beunderstood that the current flow through leads Ill and H2 will be soregulated that the arm 13 will be allowed to cool at such rate as willproduce the time lag desiredy I claim:

1. A motor starting and safety switch consisting of a suitableenlongated base having adjacent one end thereof a stationary contactadapted to be connected to the running windings of a motor and a secondstationary contact adapted to be connected to the starting windings ofsaid motor, a spring arm fixed to the other end of said base andcarrying a contact at its free end, adapted to co-act with the firstmentioned stationary contact to complete the running circuit, a secondarm fixed to said other end of said base and carrying at its free end acontact adapted to co-act with the second stationary contact to completethe starting circuit through said motor, said secnd arm being connectedto a source of current supply and being of bi-metal adapted to flex whenheated, said second arm when unheated having its contact in circuitclosing relation with the second stationary contact, a flexibl conductorfixed to said bi-metal arm and to the contact carried by said springarmyand a spring toggle member between said bi-metal arm and said springarm and adapted to move said spring arm and contact away from itsco-acting stationary contact when the bi-metal is undul flexed due toexcessive'heating.

2. A motor starting and safety switch consisting of a base member, aspring arm fixed thereto and carrying a contact at its free end, a fixedcontact normally touching the first contact, a second conducting armadapted to flex when heated fixed to said base and arranged in generallyparallel relation to the spring arm said second arm having a contactadjacent its free end, a fixed contact which the contact on said secondarm touches when cold, a toggle spring cooperating with the free ends ofsaid arms and arranged to press together the contact on said spring armand its cooperating fixed contact when said second arm is subjected tonormal heating and normal flexing and to separate the spring arm contactand its fixed contact when the second arm is subjected to abnormalheating and thereby abnormal flexing.

3. An electric switch consisting of an elongated base having flxed atone end thereof a spring arm and a bi-metallic conducting arm generallyparallel therewith, means for connecting said bimetallic arm to acurrent source, a contact fixed to the free end of each arm, a pair ofstationary {contacts fixed to saidbase and adapted to coact withrespective arm carried contacts, and to lie in circuit closing positionwhen cold, said bimetal arm adapted to flex when heated by passage ofcurrent therethrough and thereby separate its contact from its co-actingfixed contact, and a spring toggle member acting between said bi-m'etalarm and said spring arm and adapted to separate the spring arm carriedcontact from its co-acting 'flxed contact when through excessive heatingsaid bi-metal .arm is unduly flexed.

4. A motor control electric switch consisting of an elongated basehaving fixed at one end thereof a spring arm and a bi-metallicconducting arm generally parallel therewith, means for connecting saidbi-metallic arm to a current source, a contact fixed to the free end ofeach arm, a pair of stationar contacts flxed to said base and adapted tocoact with respective arm-carried contacts in circuit closing positionwhen said bimetal arm is cold, means for connecting the fixed contactcoacting with the spring arm carried contact to the motor, said bi-metalarm adapted to flex when heated by passage of current therethrough andthereby separate its contact from its coacting fixed contact, a springtoggle member acting between said arms to maintain under normal heatingthe circuit closed relation of the contact on said spring arm and itscoacting fixed contact and to separate the latter under abnormalheating, a second pair of fixed contacts with which the arm carriedcontacts are adapted to coact when said arm has been moved due toexcessive heating, at least one of said second pair of fixed contactsbeing connected in a circuit other than the motor circuit and to therebyincrease the cooling time for said bi-metal arm.

ALFRED R. LUCAS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Obszarny June 19, 1945

